This invention relates to anti-friction pistons and is an improvement over the piston disclosed in U.S. Pat. No. 3,398,653 issued to the same inventor on Aug. 27, 1968. The pistons of both the earlier patent and instant invention include roller bearings each bearing including multiple rollers 30a mounted on an axle in the piston skirt so that friction may be reduced between the piston and a cylinder in which it reciprocates.